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Adjustment Factors for more than three current carrying conductors

J

jeramiepluemer

Member
Location
Wisconsin
Occupation
Electrician
Table 310.15(B)(3)(a)

I install Generac 100 amp select circuit switches. We have to move over the hot and neutral of each circuit. We are using coupling and box adaptors to connect the panels. 1 1/4. I was told I could only have 9 current-carrying conductors in the coupling. Even if I used a 2 in coupling, it doesn't matter. Is this where I post something for Mike to make a video on Facebook? Thanks for your help. Also Neutral counts.
 
infinity

infinity

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Staff member
Location
New Jersey
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Journeyman Electrician
Whoever told you that you can only have 9 CCC's is incorrect. Derating does not apply to a raceway that is 24" or less. Also conduit fill is 60% for a nipple 24" or less so stuff away.
 
Dennis Alwon

Dennis Alwon

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Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
310.15(C)

(C) Adjustment Factors.

(1) More than Three Current-Carrying Conductors.
The ampacity of each conductor shall be reduced as shown in Table 310.15(C)(1) where the number of current-carrying conductors in a raceway or cable exceeds three, or where single conductors or multiconductor cables not installed in raceways are installed without maintaining spacing for a continuous length longer than 600 mm (24 in.). Each current-carrying conductor of a paralleled set of conductors shall be counted as a current-carrying conductor.
Where conductors of different systems, as provided in 300.3, are installed in a common raceway or cable, the adjustment factors shown in Table 310.15(C)(1) shall apply only to the number of power and lighting conductors.
 
Dennis Alwon

Dennis Alwon

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Location
Chapel Hill, NC
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Retired Electrical Contractor
Little Bill said:
What you quoted is for bundling, or without a raceway.
Click to expand...
My bad. It is still there just a few lines down from where I posted.

(C) Adjustment Factors.

(1) More than Three Current-Carrying Conductors.

The ampacity of each conductor shall be reduced as shown in Table 310.15(C)(1) where the number of current-carrying conductors in a raceway or cable exceeds three, or where single conductors or multiconductor cables not installed in raceways are installed without maintaining spacing for a continuous length longer than 600 mm (24 in.). Each current-carrying conductor of a paralleled set of conductors shall be counted as a current-carrying conductor.
Where conductors of different systems, as provided in 300.3, are installed in a common raceway or cable, the adjustment factors shown in Table 310.15(C)(1) shall apply only to the number of power and lighting conductors.
Informational Note No. 1:
See Informative Annex B for adjustment factors for more than three current-carrying conductors in a raceway or cable with load diversity.
Informational Note No. 2:
See 366.23 for adjustment factors for conductors and ampacity for bare copper and aluminum bars in auxiliary gutters and 376.22(B) for adjustment factors for conductors in metal wireways.

  • (a)
    Where conductors are installed in cable trays, 392.80 shall apply.
  • (b)
    Adjustment factors shall not apply to conductors in raceways having a length not exceeding 600 mm (24 in.).
  • (c)
    Adjustment factors shall not apply to underground conductors entering or leaving an outdoor trench if those conductors have physical protection in the form of rigid metal conduit, intermediate metal conduit, rigid polyvinyl chloride conduit (PVC), or reinforced thermosetting resin conduit (RTRC) having a length not exceeding 3.05 m (10 ft), and if the number of conductors does not exceed four.
  • (d)
    Adjustment factors shall not apply to Type AC cable or to Type MC cable under the following conditions:
    • (1)
      The cables do not have an overall outer jacket.
    • (2)
      Each cable has not more than three current-carrying conductors.
    • (3)
      The conductors are 12 AWG copper.
    • (4)
      Not more than 20 current-carrying conductors are instal⁠led without maintaining spacing, are stacked, or are supported on “bridle rings.”

Exception to (4):
If cables meeting the requirements in 310.15(C)(1)(d)(1) through (C)(1)(d)(3) with more than 20 current-carrying conductors are installed longer than 600 mm (24 in.) without maintaining spacing, are stacked, or are supported on bridle rings, a 60 percent adjustment factor shall be applied.
 
don_resqcapt19

don_resqcapt19

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Location
Illinois
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retired electrician
infinity said:
Whoever told you that you can only have 9 CCC's is incorrect. Derating does not apply to a raceway that is 24" or less. Also conduit fill is 60% for a nipple 24" or less so stuff away.
Click to expand...
Maybe he was taking to an electrician from Chicago. :D
In the Chicago 2018 Electrical Code, which is a highly amended version of the 2017 NEC, the following was added to 310.15(B)(3)(a):
“No more than nine current-carrying conductors shall be permitted to be installed in a raceway.”
The Table 310.15(B)(3)(a) was also amended to delete everything after the second row.
 
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